Field of the Invention
The present invention relates to a machine tool having a numeric control device, and more particularly, a machine tool having a numeric control device having a function for notifying information about the position of the center of gravity of a main body.
Description of the Related Art
When a machine tool is relatively small and light weight, the machine tool is often moved a short distance. Another moving method includes a method for lifting the machine tool using a crane and the like, or raising the machine using lifts such as a dolly, a forklift, and a hand lift. In particular, since the lift itself is small, the method using the lift is often used for a work of moving and installing the machine in a relatively short distance such as within a building of a factory and the like.
As described above, when raising the machine using the lift, it is necessary to determine the position and the width of the fork so that the center of gravity of the machine is located between the two forks provided with the lift, in order to prevent the falling accident of the machine and the like. When the positions or the width of the fork are thus determined, it is necessary to find the position of the center of gravity of the machine.
JP 2005-131715 A discloses a transport auxiliary device for an industrial robot using a forklift including an opening and a dedicated component externally attached to a base unit so that the receiving unit of the fork is located such that the center of gravity of the entire robot is located between the two forks and it is inserted to the receiving unit of the fork while the main body of the robot maintains a stable transport.
A small machine tool may also be moved and installed using a lift. In this case, the insertion position of the lift is not determined in many cases, and when the position of a movable unit and the weight of a load placed on the movable unit such as the upper surface of the table are not the same on every moving work, the position of the center of gravity is also not the same, and therefore, it is necessary to determine the position of the lift in accordance with the position of the center of gravity.
JP 2010-211467 A discloses a machine tool having a numeric control device, in which the weight of the load is automatically estimated, and the performance of the acceleration/deceleration of the movable unit is determined by multiple parameters defining a time constant and a command value of a moving speed optimized based on the information.
In the positioning work of the lift in the technique described in conventional techniques and JP 2005-131715 A, the position of the center of gravity is predicted, and the lift is raised at a temporary position, and the position is corrected in view of the balance, and this is repeatedly tried several times, so that a stable position is ultimately determined. In this case, when the position of the center of gravity predicted at first is significantly different from the true position of the center of gravity, the number of times the correction is tried increases, which increase the number of steps, and when raising and lowering is repeated, stress may be given to the mechanical components.